Muscle Growth Flowchart

Internal tension rises as the muscle fiber contracts. External tension rises more slowly as the series elastic elements are stretched. (a) During a single-twitch contraction, external tension cannot rise as high as internal tension before the relaxation phase begins. (b) During a tetanic contraction, external tension soon plateaus at a level roughly equivalent to internal tension. External tension remains elevated for the duration of the contraction.

Muscle fibers of different motor units are intermingled, so the forces applied to the tendon remain roughly balanced regardless of which muscle groups are stimulated. (b) The tension applied to the tendon remains relatively constant even though individual motor units cycle between contraction and relaxation.

Possible mechanism of activation of ERK1/2 and AP-1 in skeletal muscles. Schematic representation of the potential mechanism of activation of ERK1/2 and AP-1 transcription factor in response to mechanically loading of skeletal muscles either axially or transversely as supported by the data. Despite activation of ERK1/2 by either form of mechanical stress, the MEK1/2, PI3K, and PKC are involved in the activation of ERK1/2 in response to axial mechanical stress whereas PKA is involved only in response to applied transverse stress.

Allright that comprises the bulk of what I can contribute. The rest is in study papers and if anyone would like links or copies just let me know. I do have some stuff on the influence of endogeneous hormone introduction if anyone wishes.

If anyone can fill in the blanks please do as I am very interested, obvioulsy

I dug deeper in my filing system and came up with this, this I like I wish I had more.

The mitogen-activated protein (MAP) kinase intracellular signaling pathway (adopted from Ref. 74). After stimulation, a variety of known and unknown upstream regulators lead to the sequential phosphorylation and activation of a MAP kinase kinase kinase (MAPKKK) and subsequently a MAP kinase kinase (MAPKK). The MAPKK can then phosphorylate (P) and activate MAP kinase (MAPK) on conserved threonine and tyrosine residues. Activated MAP kinase phosphorylates numerous substrates, resulting in various biological effects.

IGF-I and &quot;myogenesis&quot; during compensatory hypertrophy. Increased loading leads to satellite cell proliferation, differentiation, and fusion. IGF-I has been shown to stimulate these myogeninc processes in skeletal muscles. It is postulated that IGF-I, and/or the loading-sensitive IGF-I isoform mechanogrowth factor (MGF), is produced and released by myofibers in response to increased loading or stretch. The increased local concentration of IGF-I (MGF) would then stimulate the myogenic processes needed to drive the hypertrophy response.

Quote[/b] (mikeynov @ Nov. 09 2004,8:33)]Wow, this thread is dynamite good. It should be a sticky imho.
Glad to see you've also earned your wings with the 'HST Expert' distinction. This is very well earned, in my esitmation

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Thanks Michael. Coming from someone as educated as you, I feel blessed. Now add to it.

Some of your diagroms stated that some of these chemicals regulate gene regulation and transcription. How exactly do they do this? What do they do to genes?

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First they are not MY diagrams, these I pulled from various studies that I have compiled when following what Bryan suggested, read the reviews then work through the recitations to get a good understanding of the hypertrophy processes.

From my limited understanding, genes are either turned on or off by outside events, in hypertrophy all the events have not been identified, but many have, as you've seen in the diagrams from the studies above. As far what exactly turns them on to induce growth is complicated and I don't fully understand it all, as it would take someone who is educated more than myself in molecular biology. But here is a quick down and dirty synopsis that I have in my files.

[b said:

Quote[/b] ]To create an enzyme, the cell must first transcribe the gene in the DNA into messenger RNA. The transcription is performed by an enzyme called RNA polymerase. RNA polymerase binds to the DNA strand at the promoter, unlinks the two strands of DNA and then makes a complementary copy of one of the DNA strands into an RNA strand. RNA, or ribonucleic acid, is very similar to DNA except that it is happy to live in a single-stranded state (as opposed to DNA's desire to form complementary double-stranded helixes). So the job of RNA polymerase is to make a copy of the gene in DNA into a single strand of messenger RNA (mRNA).

The strand of messenger RNA then floats over to a ribosome, possibly the most amazing enzyme in nature. A ribosome looks at the first codon in a messenger RNA strand, finds the right amino acid for that codon, holds it, then looks at the next codon, finds its correct amino acid, stitches it to the first amino acid, then finds the third codon, and so on. The ribosome, in other words, reads the codons, converts them to amino acids and stitches the amino acids together to form a long chain. When it gets to the last codon -- the stop codon -- the ribosome releases the chain. The long chain of amino acids is, of course, an enzyme. It folds into its characteristic shape, floats free and begins performing whatever reaction that enzyme performs.

Obviously, the process described on the previous page is not a simple one. A ribosome is an extremely complex structure of enzymes and ribosomal RNA (rRNA) bonded together into a large molecular machine. A ribosome is helped by ATP, which powers it as it walks along the messenger RNA and as it stitches the amino acids together. It is also helped by transfer RNA (tRNA), a collection of 20 special molecules that act as carriers for the 20 different individual amino acids. As the ribosome moves down to the next codon, the correct tRNA molecule, complete with the correct amino acid, moves into place. The ribosome breaks the amino acid off the tRNA and stitches it to the growing chain of the enzyme. The ribosome then ejects the &quot;empty&quot; tRNA molecule so it can go get another amino acid of the correct type.

An RNA polymerase enzyme attaches to a DNA strand at a gene's promoter. It then walks down the DNA and creates a copy of it into a strand of messenger RNA (mRNA).

The mRNA strand floats free and finds a ribosome.
A ribosome attaches to and walks down the mRNA strand to form a chain of amino acids for the enzyme that the gene represents. The amino-acid chain folds into the enzyme's characteristic shape and starts doing its thing.

There are RNA polymerase enzymes attaching to the DNA strand at the starting points of different genes and copying the DNA for the gene into an mRNA molecule.
The mRNA molecule floats over to a ribosome, which reads the molecule and stitches together the string of amino acids that it encodes.

The string of amino acids floats away from the ribosome and folds into its characteristic shape so it can start catalyzing its specific reaction.

The cytoplasm of any cell is swimming with ribosomes, RNA polymerases, tRNA and mRNA molecules and enzymes, all carrying out their reactions independently of each other.

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Now to see how all this deals with Hypertrophy, you might want to read these studies.